1. Field of the Invention
The present invention relates generally to the field of fuel tank trailers. More specifically, the present invention discloses a fuel tank trail with a secondary containment wall and filter for separating fuel from water.
2. Description of the Relevant Art
Statement of the Problem
Fuel tank trailers have been widely used for many years. Some fuel tank trailers are little more than a fuel tank with wheels and a trailer hitch, but this provides no means for secondary containment of fuel leaking or spilling from the tank. One approach to this problem has been to use a double-walled tank. The void between the tank walls provides a secondary containment region for any fuel leaking from the inner tank. However, double-walled tanks are significantly more expensive to construct. In addition, it can be difficult to detect leakage from the inner tank, particularly at the initial stages of a leakage problem if only a small amount of fuel is escaping from the inner tank. Some double-walled tanks attempt to address this problem by installing a sight glass or access port into the secondary containment region between the tank walls. Nonetheless, it is advantageous to be able to visually inspect as much of the exterior surface of the fuel tank as possible so that leakage problems can be detected as soon as possible.
Secondary containment walls or berms have also been widely used for many years, particular for stationary fuel tanks. For example, large fuel tanks in tank farms are typically surrounded by an earthen berm for secondary containment. Many smaller stationary fuel tanks and other types of tanks for containing flammable or hazardous liquids are also equipped with a secondary containment wall or berm.
One problem associated with an open secondary containment region is that rain water, dew, and melting snow can also accumulate in the secondary containment region and result in a mixture of fuel and water. This mixture presents a fire hazard and an environmental risk, and so cannot be readily disposed of without treatment. This poses a significant problem and has been viewed as a significant limitation of open secondary containment systems. Therefore, a need exists for a open secondary containment system that provides a means for addressing the problem of fuel and water accumulating in the secondary containment region.
The prior art in this field includes the following: TABLE-US-00001 Inventor patent No. Issue Date Erickson U.S. Pat. No. 6,715,195 Apr. 6, 2004 Page U.S. Pat. No. 5,232,246 Aug. 3, 1993 Marino U.S. Pat. No. 5,071,166 Dec. 10, 1991 Morris U.S. Pat. No. 4,482,017 Nov. 13, 1984 Kerr U.S. Pat. No. 3,604,719 Sep. 14, 1971 Dascanio U.S. Pat. No. 3,352,461 Nov. 14, 1967 Kachnik U.S. Pat. No. 3,263,865 Aug. 2, 1966 Brehany et al. U.S. Pat. No. 2,567,164 Sep. 11, 1951 Taylor U.S. Pat. No. 2,421,765 Jun. 10, 1947.
Marino discloses a transportable holding tank that has an inner tank and a surrounding rigid enclosure for containment. Marino's tank assembly has small wheels at one end of the support frame.
Brehany et al. disclose a portable double-walled tank.
Kerr discloses a towable liquid storage tank that is held by a tub-like saddle.
Erickson discloses a towable tank for mixing and delivering material, such as asphalt. An agitation member is used for mixing within the tank.
Taylor discloses a tank with multiple compartments. The remaining references are only of passing interest.
Solution to the Problem
None of the prior art references discussed above show a fuel tank trailer having an open secondary containment region and a fuel separation filter to separate water from any fuel collecting in the secondary containment region. This approach combines the advantages of an open secondary containment system with a convenient of means for treating the fuel/water mixture.